Patients with well-documents chronic non-A, non-B (non-lupoid) hepatitis are being evalutated to determine the natural history of this disease and to obtain tissues and reagents to search for non-A, non-B agents. Twenty-eight patients have been admitted to this study. These patients have undergone thorough evaluation including a liver biopsy. They have had the disease for periods ranging from 1 to 10 years. Six patients have a mild degfree of malaise, the remaining patients are asymptomatic. Liver biopsies have revealed chroinic persistent hepatitis in six, chronic active hepatitis in twenty, and alcoholic liver disease in two. Six patients have developed cirrhosis. These studies have provided a framework for trials of immunosuppressive and antiviral therapy. A pilot study of Acyclovir therapy has been initiated.